[PATCH v2 3/5] spi: spi-mtk-nor: use dma_alloc_coherent() for bounce buffer

[Ikjoon Jang]

Use dma_alloc_coherent() for bounce buffer instead of kmalloc.

Signed-off-by: Ikjoon Jang <ikjn@xxxxxxxxxxxx>

---

(no changes since v1)

 drivers/spi/spi-mtk-nor.c | 60 +++++++++++++++++++++++----------------
 1 file changed, 35 insertions(+), 25 deletions(-)

diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
index 54b2c0fde95b..e14798a6e7d0 100644
--- a/drivers/spi/spi-mtk-nor.c
+++ b/drivers/spi/spi-mtk-nor.c
@@ -96,6 +96,7 @@ struct mtk_nor {
 	struct device *dev;
 	void __iomem *base;
 	u8 *buffer;
+	dma_addr_t buffer_dma;
 	struct clk *spi_clk;
 	struct clk *ctlr_clk;
 	unsigned int spi_freq;
@@ -275,19 +276,16 @@ static void mtk_nor_setup_bus(struct mtk_nor *sp, const struct spi_mem_op *op)
 	mtk_nor_rmw(sp, MTK_NOR_REG_BUSCFG, reg, MTK_NOR_BUS_MODE_MASK);
 }
 
-static int mtk_nor_read_dma(struct mtk_nor *sp, u32 from, unsigned int length,
-			    u8 *buffer)
+static int read_dma(struct mtk_nor *sp, u32 from, unsigned int length,
+		    dma_addr_t dma_addr)
 {
 	int ret = 0;
 	ulong delay;
 	u32 reg;
-	dma_addr_t dma_addr;
 
-	dma_addr = dma_map_single(sp->dev, buffer, length, DMA_FROM_DEVICE);
-	if (dma_mapping_error(sp->dev, dma_addr)) {
-		dev_err(sp->dev, "failed to map dma buffer.\n");
+	if (WARN_ON((length & MTK_NOR_DMA_ALIGN_MASK) ||
+		    (dma_addr & MTK_NOR_DMA_ALIGN_MASK)))
 		return -EINVAL;
-	}
 
 	writel(from, sp->base + MTK_NOR_REG_DMA_FADR);
 	writel(dma_addr, sp->base + MTK_NOR_REG_DMA_DADR);
@@ -312,30 +310,39 @@ static int mtk_nor_read_dma(struct mtk_nor *sp, u32 from, unsigned int length,
 					 (delay + 1) * 100);
 	}
 
-	dma_unmap_single(sp->dev, dma_addr, length, DMA_FROM_DEVICE);
 	if (ret < 0)
 		dev_err(sp->dev, "dma read timeout.\n");
 
 	return ret;
 }
 
-static int mtk_nor_read_bounce(struct mtk_nor *sp, u32 from,
-			       unsigned int length, u8 *buffer)
+static int mtk_nor_read_dma(struct mtk_nor *sp, u32 from,
+			    unsigned int length, u8 *buffer)
 {
-	unsigned int rdlen;
 	int ret;
+	dma_addr_t dma_addr;
+	bool bounce = need_bounce(buffer, length);
 
-	if (length & MTK_NOR_DMA_ALIGN_MASK)
-		rdlen = (length + MTK_NOR_DMA_ALIGN) & ~MTK_NOR_DMA_ALIGN_MASK;
-	else
-		rdlen = length;
+	if (!bounce) {
+		dma_addr = dma_map_single(sp->dev, buffer, length,
+					  DMA_FROM_DEVICE);
+		if (dma_mapping_error(sp->dev, dma_addr)) {
+			dev_err(sp->dev, "failed to map dma buffer.\n");
+			return -EINVAL;
+		}
+	} else {
+		dma_addr = sp->buffer_dma;
+	}
 
-	ret = mtk_nor_read_dma(sp, from, rdlen, sp->buffer);
-	if (ret)
-		return ret;
+	ret = read_dma(sp, from, length, dma_addr);
 
-	memcpy(buffer, sp->buffer, length);
-	return 0;
+	if (!bounce)
+		dma_unmap_single(sp->dev, dma_addr, length,
+				 DMA_FROM_DEVICE);
+	else
+		memcpy(buffer, sp->buffer, length);
+
+	return ret;
 }
 
 static int mtk_nor_read_pio(struct mtk_nor *sp, const struct spi_mem_op *op)
@@ -439,11 +446,6 @@ static int mtk_nor_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
 		if (op->data.nbytes == 1) {
 			mtk_nor_set_addr(sp, op);
 			return mtk_nor_read_pio(sp, op);
-		} else if (((ulong)(op->data.buf.in) &
-			    MTK_NOR_DMA_ALIGN_MASK)) {
-			return mtk_nor_read_bounce(sp, op->addr.val,
-						   op->data.nbytes,
-						   op->data.buf.in);
 		} else {
 			return mtk_nor_read_dma(sp, op->addr.val,
 						op->data.nbytes,
@@ -654,6 +656,10 @@ static int mtk_nor_probe(struct platform_device *pdev)
 	sp->dev = &pdev->dev;
 	sp->spi_clk = spi_clk;
 	sp->ctlr_clk = ctlr_clk;
+	sp->buffer = dma_alloc_coherent(&pdev->dev, MTK_NOR_BOUNCE_BUF_SIZE,
+					&sp->buffer_dma, GFP_KERNEL);
+	if (!sp->buffer)
+		return -ENOMEM;
 
 	irq = platform_get_irq_optional(pdev, 0);
 	if (irq < 0) {
@@ -674,6 +680,8 @@ static int mtk_nor_probe(struct platform_device *pdev)
 	ret = mtk_nor_init(sp);
 	if (ret < 0) {
 		kfree(ctlr);
+		dma_free_coherent(&pdev->dev, MTK_NOR_BOUNCE_BUF_SIZE,
+				  sp->buffer, sp->buffer_dma);
 		return ret;
 	}
 
@@ -692,6 +700,8 @@ static int mtk_nor_remove(struct platform_device *pdev)
 
 	mtk_nor_disable_clk(sp);
 
+	dma_free_coherent(&pdev->dev, MTK_NOR_BOUNCE_BUF_SIZE,
+			  sp->buffer, sp->buffer_dma);
 	return 0;
 }
 
-- 
2.28.0.681.g6f77f65b4e-goog